Aperture cards have become a frequently utilized method for storing information. The standard size aperture card is 73/8 inches long and 13/4 inches wide. A microfilm piece is mounted in the aperture of the aperture card. This microfilm piece is a reduced size image of a document or drawing and has a dark background with clear letters, characters or lines appearing thereon. The microfilm piece is mounted in an aperture positioned in the same location on every card. The front edge of the microfilm is approximately 0.764 inches from the leading edge of the card, and the side edges of the microfilm are approximately 1.021 inches from the respective side edges of the aperture card.
In known aperture card printers on the market, a stack of aperture cards for printing is positioned in a supply bin. Drive rollers cooperate with a knife edge on the feed aperture from the bin to remove one card at a time from the bin. The removed card is driven by a roller system to a carriage pickup position. At such position, glass flats are clamped on both sides of the microfilm piece to hold it in a flattened condition. The glass flats are mounted on a reciprocally driven carriage.
With the microfilm in the aperture card sandwiched between the opposed glass flats, the carriage is advanced through an optics system to scan the image on the microfilm piece for printing. When the microfilm piece has been advanced through and beyond the optic system, the carriage is stopped, the glass flats are opened and the aperture card is removed from the carriage by an exit roller system. The carriage with the opened glass flats is then cycled back to its pickup position to receive the next aperture card for printing.
The conventional aperture card transport system consists of a series of interrupted reciprocal movements. One aperture card cannot be fed directly after another aperture card through the optics system because of such interrupted reciprocal motions. As such, the printing speed of this system is relatively slow with the capacity to make approximately ten prints per minute. In addition, with the feeding and clamping motions involved, the handling of the aperture card is relatively rough and may cause damage to the card or microfilm, particularly when attempts are made to speed up the printing process. This may shorten the life of the aperture card and/or the microfilm piece carried thereby.
In addition, the glass flats with their repeated reciprocal clamping actions are subject to wear, scratches and mis-alignment and are also continually exposed to dust and dirt. Scratches, dust or dirt on the glass flats positioned on opposite sides of the microfilm piece create image imperfections when the microfilm piece is optically scanned resulting in image imperfections on the print made. In addition, the glass flats are subject to continuing maintenance problems and must be replaced from time to time.